1. Field of the Invention
The present invention relates to single-wafer-processing type CVD (Chemical Vapor Deposition) which forms a thin film on a semiconductor wafer, which is an object-to-be-processed.
2. Description of the Related Art
Due to high integration of a semiconductor apparatus, interconnects using Cu, which has lower electrical resistance than Al interconnects which were used in the past, have come into use. Additionally, when Cu is used for interconnects, it becomes necessary to form a metal film such as TiN, TaN, etc., which had not conventionally been used before, as a barrier metal for preventing diffusion of Cu. In the present circumstances, sputtering is the favored deposition method of forming these barrier metal films. In the case of Cu interconnects, after a seed layer of a thin film is formed by sputtering, Cu is deposited by plating. In the future, however, further advance of high integration is inevitable, and deposition by CVD which has better step coverage than PVD (Physical Vapor Deposition or sputtering) will become important. If a metal film whose effects on these metal films or a semiconductor apparatus have not been known is deposited using a conventional CVD apparatus, contamination of semiconductor production lines is likely to be caused by metal contamination of the back side or an edge of objects-to-be-processed, lowering yield. To solve such problems, a special apparatus for cleaning the back side and the edge of wafers conventionally had become required. For this reason, a method of suppressing deposition of the back side and the edge by mechanically clamping the edge of semiconductor wafers has been used. This method creates a different set of problems such as damaging semiconductor wafers and generating particles. Additionally, with these metal films, because conventional methods cannot be used for cleaning inside a deposition apparatus, it is critical not to accumulate the metals inside a reaction chamber as much as possible to improve throughput.